RESUMEN
We report here on a case of persistent proatlantal artery type I with the absence of the right vertebral artery's first, second and third segments. This rare anomaly was accidentally encountered when performing angiography in a patient with a ruptured aneurysm of the left anterior choroidal artery and an unruptured aneurysm of the right anterior choroidal artery. Both aneurysms were clipped via craniotomy. The angiography showed that the right proatlantal artery type I arose from the right internal carotid artery at the C2 level. The proatlantal artery joined the horizontal portion of the right vertebral artery. The absence of the right vertebral artery's first, second and third segments and a hypoplastic left vertebral artery were demonstrated. The anomalous artery was thought to have been unrelated to rupture of the aneurysm. We also reviewed the previous Korean reports about a persistent proatlantal artery, and we discuss the potential clinical implications of this anomalous vessel.